node.java

一个可以在applet窗体上持行sql语句并显示返回结果的程序

/*
 * Node.java
 */

package org.hsql;
import java.sql.*;
import java.io.*;

class Node {
  int iBalance; // currently, -2 means 'deleted'
  int iLeft,iRight,iParent;
  Node nLeft,nRight,nParent;
  private int iId;  // id of index this table
  Node nNext; // node of next index (nNext==null || nNext.iId=iId+1)
  Row rData;
  Node(Row r,DataInput in,int id) throws IOException,SQLException {
    iId=id;
    rData=r;
    iBalance=in.readInt();
    iLeft=in.readInt();
    iRight=in.readInt();
    iParent=in.readInt();
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
  }
  Node(Row r,int id) {
    iId=id;
    rData=r;
  }
  void delete() {
    iBalance=-2;
    nLeft=nRight=nParent=null;
    iLeft=iRight=iParent=0;
  }
  int getKey() {
    return rData.iPos;
  }
  Node getLeft() throws SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    if(iLeft==0) {
      return nLeft;
    }
    rData.iLastAccess=Row.iCurrentAccess++;
    return rData.getNode(iLeft,iId);
  }
  void setLeft(Node n) throws SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    rData.changed();
    if(n==null) {
      iLeft=0;
      nLeft=null;
    } else if(n.rData.iPos!=0) {
      iLeft=n.rData.iPos;
    } else {
      nLeft=n;
    }
  }
  Node getRight() throws SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    if(iRight==0) {
      return nRight;
    }
    rData.iLastAccess=Row.iCurrentAccess++;
    return rData.getNode(iRight,iId);
  }
  void setRight(Node n) throws SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    rData.changed();
    if(n==null) {
      iRight=0;
      nRight=null;
    } else if(n.rData.iPos!=0) {
      iRight=n.rData.iPos;
    } else {
      nRight=n;
    }
  }
  Node getParent() throws SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    if(iParent==0) {
      return nParent;
    }
    rData.iLastAccess=Row.iCurrentAccess++;
    return rData.getNode(iParent,iId);
  }
  void setParent(Node n) throws SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    rData.changed();
    if(n==null) {
      iParent=0;
      nParent=null;
    } else if(n.rData.iPos!=0) {
      iParent=n.rData.iPos;
    } else {
      nParent=n;
    }
  }
  int getBalance() throws SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    //rData.iLastAccess=Row.iCurrentAccess++;
    return iBalance;
  }
  void setBalance(int b) throws SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    if(iBalance!=b) {
      rData.changed();
      iBalance=b;
    }
  }
  public Object[] getData() throws SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    return rData.getData();
  }
  boolean equals(Node n) throws SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    rData.iLastAccess=Row.iCurrentAccess++;
    if(Trace.ASSERT) {
      if(n!=this) {
        Trace.assert(rData.iPos==0 || n==null || n.rData.iPos!=rData.iPos);
      } else {
        Trace.assert(n.rData.iPos==rData.iPos);
      }
    }
    return n==this;
  }
  void write(DataOutput out) throws IOException,SQLException {
    if(Trace.ASSERT) Trace.assert(iBalance!=-2);
    out.writeInt(iBalance);
    out.writeInt(iLeft);
    out.writeInt(iRight);
    out.writeInt(iParent);
    if(nNext!=null) {
      nNext.write(out);
    }
  }
}